The present invention relates to a battery cell having a cell housing that comprises a housing container and a housing cover, two electrodes that are arranged in an inner region of the housing container, an electrolyte material that is arranged in the inner region of the housing container and surrounds the electrodes, and two electrical contacts that are electrically coupled in each case to one of the electrodes and extend from the inner region of the housing container through the housing cover into a region outside the cell housing.
Moreover, the present invention relates to a method for sealing a battery cell, wherein the battery cell comprises a cell housing that comprises a housing container and a housing cover, two electrodes that are arranged in an inner region of the housing container, an electrolyte material that is arranged in the inner region of the housing container and surrounds the electrodes, and two electrical contacts that are electrically coupled in each case to one of the electrodes and extend from the inner region of the housing container through the housing cover into a region outside the cell housing.
A battery cell is an electrochemical energy storage device and an energy converter. As the battery is discharged, stored chemical energy is converted into electrical energy by means of an electrochemical reaction. The electrical energy can be used by a consumer that is electrically coupled to the battery.
In motor vehicles, a battery is used inter alia for the purpose of supplying current for the head lamps, the on-board electronics and for the starter for the purpose of starting the internal combustion engine. In electric or hybrid vehicles, the battery is also used as an energy storage device for the electrical drive of the motor vehicle.
The batteries (for example lithium ion rechargeable batteries) that are used in motor vehicles often comprise a prismatic shape in order to be able to maximize the use of the available volume. A flat-pressed wrap is provided inside the housing and said flat-pressed wrap is rolled from an aluminum film, a copper film and also two synthetic material or ceramic films that are used as diaphragms. The aluminum film and the copper film are coated with reactive cathode and anode materials. The housing is filled with a liquid electrolyte after the wrap has been introduced and prior to the pressure-tight sealing arrangement being provided.
The cathode film and the anode film of the wrap are not positioned in a matching arrangement but rather are positioned slightly offset with respect to one another in order to render it possible to provide an electrical contact to the two films. This renders it possible at the respective film to tap the negative voltage at one open narrow side of the wrap and to tap the positive voltage at the other opposite-lying narrow side. The overlapping film strips are contacted by means strip-shaped sheet metal parts that are welded on and are embodied from copper and/or aluminum, the so-called current collectors. The cell housing of a battery usually comprises a housing container and a housing cover that are produced by way of example from aluminum or stainless steel. Various aspects are to be considered when providing the contact to the above mentioned current collectors inside the cell housing and in the case of the feedthrough of the current paths through the housing towards the outside. For example, it is necessary to first electrically insulate the current paths with respect to the metal cell housing. Furthermore it is necessary to ensure the leak-tightness of the current feedthrough through the cell housing. In particular, it is necessary by way of example to prevent the electrolyte material that is located in the cell housing from outgassing into the atmosphere. Moreover, the cell housing should, without becoming damaged, be able to withstand mechanical loadings (mainly an internal pressure and pressure forces that arise by virtue of binding multiple batteries together to form one cell module) that act upon the cell housing. Since a large number of battery cells are used in a motor vehicle, it is desirable to achieve a cost-effective solution for sealing the cell housing and for absorbing mechanical loadings at the site where the housing container is connected to the housing cover.
In the case of known battery cells, the housing container and the housing cover are connected by means of a laser weld seam. The laser weld seam also assumes the function of sealing the cell housing. One problem in the case of a laser weld seam resides in the fact that during the welding process so-called weld beads (welding faults) can arise. These weld beads prevent the battery cells from lying directly one against the other. Due to the fact that the outer surfaces of the battery cells do not lie completely flat one against the other, it is not possible to ensure that the battery cells are correctly assembled to form one cell module. Furthermore, the cell housing is deformed as a result of the effects of heat that is produced during the welding process. This deformation also has a negative effect on the process of assembling the battery cells.